1. Field of the Invention
The present invention relates to an infrared ray (IR) switching device, particularly, an IR switching device being switched without touching.
2. Descriptions of the Related Art
Virus and bacteria are always brought into human bodies via their hands when people touch things. Though people remove the virus and the bacteria from hands by washing hands and disinfecting with alcohol solutions, people still have to use some switches in public places, such as turning on the light, turning off the light, pressing keys of an elevator, ringing a stop bell of a bus, etc. The virus and the bacteria would adhere to the switches. When people touch the switches, the virus and the bacteria would be bought into human bodies inevitably. To avoid diseases from spreading, a switch device for switching without touching is thus developed.
A conventional capacitance switch is known as a non-touch switch. The conventional capacitance switch emits a high frequency radio wave continuously. When there is a human body approaching, an electrostatic capacity of the human body changes an emission frequency of the high frequency radio wave. The conventional switch detects a change of the emission frequency, and then switches according to the change. The drawbacks of the conventional capacitance switch are illustrated as the following. A stability of the emission frequency is tended to be influenced by an environmental temperature. Moreover, the electrostatic capacity of the human body is tended to be influenced by an environmental humidity. Because of the disadvantages, the performance of the conventional capacitance switch is unstable, and the reliability is not ideal.
Another conventional non-touch switch is designed in a body temperature type. The body temperature switch detects an infrared ray at a wavelength 10 μm radiated from the body temperature of the human body, converts the infrared ray into an electrical signal, and then switches according to the electrical signal. Since the body temperature switch does not comprise an emission unit, this switch detects the temperature in a passive detecting manner.
The body temperature switch has some disadvantages. First of all, a distance for available detection should be large than 5 m for the normal effect of a sensor and a prefilter of the body temperature switch. If the distance is less than 1 m, the performance of the body temperature switch is unstable, and the reliability is getting worse. In the next place, the body temperature switch is only able to switch on and switch off, and is unable to switch gradually for the limitation of the sensor. Furthermore, the body temperature switch is disadaptive for an environment with surrounding heat sources, because some error may be caused by the heat sources.
Yet a further conventional non-touch switch is in an ultrasonic type. The ultrasonic switch comprises an ultrasonic transducer and an ultrasonic receiver. The ultrasonic transducer emits an ultrasonic wave, and then the ultrasonic receiver receives a reflected ultrasonic wave. After comparing the phase difference between the ultrasonic wave and the reflected ultrasonic wave, the ultrasonic switch estimates according to the comparison and then switches. The defects of the ultrasonic switch are described as below. The ultrasonic wave is a sonic wave. During transmitting through air, the speed of transmission is slow, and the transmission is tended to be influenced by the air density and the temperature and thus it results in low reliability during the period of transmission. The scale of the ultrasonic transducer is large for being restrained by the character of the sound wave, and is unsuitable for a small scale requirement of the switch. On the other hand, there is a diffraction problem of the sound wave needed to be dealt with when the ultrasonic transducer is applied within a distance less than 10 cm.
To solve the aforementioned drawbacks of the conventional non-touch switches, a non-touch switch which has high stability and high reliability, is not affected by environmental changes, and switches gradually is urgently needed.